The present invention relates to a method and apparatus for controlling the ignition timing of an internal combustion engine.
A well-known ignition timing control system of an internal combustion engine controls the ignition timing by detecting engine parameters that represent the operating conditions of an internal combustion engine, e.g., detecting the rotational speed of the engine, flow rate of the intake air, pneumatic pressure in the intake manifold, to calculate the ignition timing and to instruct the ignition at a calculated timing. In the system of this type, the ignition timing is often forcibly fixed to a predetermined constant value since the power-supply voltage supplied to the system and engine parameters which indicate the operation conditions, such as rotational speed, undergo great variation when the engine is in the starting condition. After starting, the ignition timing is controlled in an ordinary manner depending upon the detected parameters of operating conditions.
In general, however, there often develop great changes in the engine parameters such as rotational speed, flow rate of the intake air, and the like, immediately after starting of the engine. Therefore, if the ignition timing is controlled in an ordinary manner like the conventional control method just after starting, the time is not sufficient to carry the electric current to the ignition coil, and misfire develops, causing in the worst cases, the engine to stall.